U.S. patent number 7,179,929 [Application Number 10/513,314] was granted by the patent office on 2007-02-20 for method for producing conjugated linoleic acid glycerides.
This patent grant is currently assigned to Cognis Deutschland GmbH & Co. KG. Invention is credited to Juergen Gierke, Peter Horlacher, Karl-Heinz Ruf, Franz Timmermann.
United States Patent |
7,179,929 |
Horlacher , et al. |
February 20, 2007 |
Method for producing conjugated linoleic acid glycerides
Abstract
Processes for preparing conjugated fatty acid glycerides
comprising: (a) isomerizing a fatty acid lower alkyl ester
corresponding to the general formula (I) in the presence of a basic
catalyst at a temperature of from 100 to 160.degree. C., to form a
conjugated fatty acid lower alkyl ester: R.sup.1CO--OR.sup.2 (I)
wherein R.sup.1CO represents an acyl radical having from 16 to 22
carbon atoms and at least two carbon-carbon unsaturations and
R.sup.2 represents an alkyl radical having from 1 to 4 carbon
atoms; and (b) transesterifying the conjugated fatty acid lower
alkyl ester with glycerol to form a conjugated fatty acid
glyceride, wherein a lower alkanol corresponding to the general
formula R.sup.2OH is formed, wherein R.sup.2 is as defined above,
and the lower alkanol is continuously removed from the
transesterification reaction; are described.
Inventors: |
Horlacher; Peter (Bellenberg,
DE), Timmermann; Franz (Illertissen, DE),
Gierke; Juergen (Illertissen/Betlinshausen, DE), Ruf;
Karl-Heinz (Babenhausen, DE) |
Assignee: |
Cognis Deutschland GmbH & Co.
KG (Duesseldorf, DE)
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Family
ID: |
29225011 |
Appl.
No.: |
10/513,314 |
Filed: |
April 25, 2003 |
PCT
Filed: |
April 25, 2003 |
PCT No.: |
PCT/EP03/04302 |
371(c)(1),(2),(4) Date: |
November 03, 2004 |
PCT
Pub. No.: |
WO03/093214 |
PCT
Pub. Date: |
November 13, 2003 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20050176977 A1 |
Aug 11, 2005 |
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Foreign Application Priority Data
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May 3, 2002 [DE] |
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102 19 781 |
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Current U.S.
Class: |
554/124 |
Current CPC
Class: |
C07C
67/03 (20130101); C07C 67/333 (20130101); C11C
3/06 (20130101); C11C 3/14 (20130101); C07C
67/03 (20130101); C07C 69/587 (20130101); C07C
67/333 (20130101); C07C 69/587 (20130101); C07B
2200/09 (20130101) |
Current International
Class: |
C07C
51/00 (20060101) |
Field of
Search: |
;554/124 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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197 18 245 |
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Jul 1998 |
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DE |
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WO 03/022964 |
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Mar 2003 |
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WO |
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Primary Examiner: Carr; Deborah D.
Attorney, Agent or Firm: Daniels; John F.
Claims
What is claimed is:
1. A process comprising: (a) isomerizing a fatty acid lower alkyl
ester corresponding to the general formula (I) in the presence of a
basic catalyst at a temperature of from 100 to 160.degree. C., to
form a conjugated fatty acid lower alkyl ester: R.sup.1CO--OR.sup.2
(I) wherein R.sup.1CO represents an acyl radical having from 16 to
22 carbon atoms and at least two carbon-carbon unsaturations and
R.sup.2 represents an alkyl radical having from 1 to 4 carbon
atoms; and (b) transesterifying the conjugated fatty acid lower
alkyl ester with glycerol to form a conjugated fatty acid
glyceride, wherein a lower alkanol corresponding to the general
formula R.sup.2OH is formed, wherein R.sup.2 is as defined above,
and the lower alkanol is continuously removed from the
transesterification reaction.
2. The process according to claim 1, wherein the fatty acid lower
alkyl ester comprises a mixture of fatty acid lower alkyl esters
corresponding to the general formula (I), wherein a predominant
portion of the mixture is comprised of fatty acid lower alkyl
esters corresponding to the general formula (I) wherein R.sup.1CO
represents an acyl radical having from 16 to 22 carbon atoms and at
least two carbon-carbon unsaturations.
3. The process according to claim 2, wherein at least 50 mole % of
the mixture is comprised of fatty acid lower alkyl esters
corresponding to the general formula (I) wherein R.sup.1CO
represents an acyl radical having from 16 to 22 carbon atoms and at
least two carbon-carbon unsaturations.
4. The process according to claim 2, wherein at least 60 mole % of
the mixture is comprised of fatty acid lower alkyl esters
corresponding to the general formula (I) wherein R.sup.1CO
represents an acyl radical having from 16 to 22 carbon atoms and at
least two carbon-carbon unsaturations.
5. The process according to claim 2, wherein the mixture of fatty
acid lower alkyl esters comprises a component selected from the
group consisting of sunflower fatty acid esters, safflower fatty
acid esters, rapeseed fatty acid esters and mixtures thereof.
6. The process according to claim 2, wherein the mixture of fatty
acid lower alkyl esters comprises safflower fatty acid esters.
7. The process according to claim 1, wherein R.sup.2 represents an
alkyl radical having from 1 to 2 carbon atoms.
8. The process according to claim 2, wherein the mixture of fatty
acid lower alkyl esters comprises methyl or ethyl esters.
9. The process according to claim 3, wherein the mixture of fatty
acid lower alkyl esters comprises methyl or ethyl esters.
10. The process according to claim 6, wherein the mixture of fatty
acid lower alkyl esters comprises methyl or ethyl esters.
11. The process according to claim 1, wherein the basic catalyst
comprises a basic component selected from the group consisting of
alkali metal hydroxides, alkali metal alkoxides and mixtures
thereof.
12. The process according to claim 2, wherein the basic catalyst
comprises a basic component selected from the group consisting of
alkali metal hydroxides, alkali metal alkoxides and mixtures
thereof.
13. The process according to claim 3, wherein the basic catalyst
comprises a basic component selected from the group consisting of
alkali metal hydroxides, alkali metal alkoxides and mixtures
thereof.
14. The process according to claim 5, wherein the basic catalyst
comprises a basic component selected from the group consisting of
alkali metal hydroxides, alkali metal alkoxides and mixtures
thereof.
15. The process according to claim 1, wherein the isomerization is
carried out over a period of from 1 to 6 hours.
16. The process according to claim 1, wherein the conjugated fatty
acid lower alkyl ester and the glycerol are reacted in a molar
ratio of from 1:0.3 to 1:0.5.
17. The process according to claim 1, wherein the
transesterification reaction is carried out at temperatures of from
100 to 160.degree. C.
18. The process according to claim 2, wherein the mixture of fatty
acid lower alkyl esters is isomerized to form a mixture of
conjugated fatty acid lower alkyl esters, and the mixture of
conjugated fatty acid lower alkyl esters is transesterified with
glycerol to form a mixture of conjugated fatty acid glycerides,
wherein the mixture of conjugated fatty acid glycerides contains
less than 3% by weight of conjugated linoleic acid moieties having
trans-trans double bonds, based on the total content of conjugated
linoleic acid moieties.
19. The process according to claim 2, wherein the mixture of fatty
acid lower alkyl esters is isomerized to form a mixture of
conjugated fatty acid lower alkyl esters, and the mixture of
conjugated fatty acid lower alkyl esters is transesterified with
glycerol to form a mixture of conjugated fatty acid glycerides,
wherein the mixture of conjugated fatty acid glycerides contains at
least 95% by weight of c9,t11- and t10,c12-isomers of conjugated
linoleic acid moieties, based on the total content of conjugated
linoleic acid moieties.
20. A process comprising: (a) isomerizing a mixture of fatty acid
lower alkyl esters corresponding to the general formula (I) to form
a conjugated fatty acid methyl ester, in the presence of a basic
catalyst comprising a basic component selected from the group
consisting of alkali metal hydroxides, alkali metal alkoxides and
mixtures thereof at a temperature of from 100 to 160.degree. C.:
R.sup.1CO--OR.sup.2 (I) wherein a predominant portion of the
mixture is comprised of fatty acid methyl esters corresponding to
the general formula (I) wherein R.sup.1CO represents an acyl
radical having from 16 to 22 carbon atoms and at least two
carbon-carbon unsaturations; and (b) transesterifying the
conjugated fatty acid methyl ester with glycerol to form a
conjugated fatty acid glyceride, wherein methanol is formed, and
the methanol is continuously removed from the transesterification
reaction.
Description
This application is a 371 of PCT/EP03/04302 filed Apr. 25,
2003.
TITLE OF THE INVENTION
Processes for Preparing Conjugated Fatty Acid Glycerides
BACKGROUND OF THE INVENTION
Linoleic acid having conjugated double bonds, which are on the
market under the name "CLA" (conjugated linoleic acid), are
physiologically active and are used as food additives. A
disadvantage is that they are highly hydrophilic and are therefore
only incorporated into oil phases or absorbed by fats with
difficulty. In addition, they can undergo unwanted reactions with
other food constituents, which leads to sensory disadvantages
(taste, odor, coloration) and is therefore undesirable. The problem
can be avoided if, instead of the free acids, the corresponding
triglycerides are used. According to the methods of the prior art,
as represented, for example, by German patent DE 19718245 C2
(Cognis), although these conjugated linoleic acid glycerides can be
synthesized in principle, it is a disadvantage that they have a
comparatively high content of physiologically inactive and unwanted
trans, trans-double-bond isomers.
It is therefore an object of the present invention to develop an
improved method of preparing conjugated linoleic acid glycerides
which is successful with very low equipment requirements and
secondly provides products which are distinguished by a very low
content of trans, trans-double-bond isomers and a very high content
of c9,t11- and t10,c12-isomers.
BRIEF SUMMARY OF THE INVENTION
The present invention relates, in general, to food additives and
relates to an improved one-pot method of preparing conjugated fatty
acid glycerides, especially specific conjugated linoleic acid
glycerides.
The invention relates to a method for preparing conjugated linoleic
acid glycerides having a reduced content of trans, trans-isomers
which comprises (a) subjecting fatty acid low-alkyl esters of the
formula (I), R.sup.1CO--OR.sup.2 (I) where R.sup.1CO is a
predominantly polyunsaturated acyl radical having 16 to 22,
preferably 18 to 20, carbon atoms and R.sup.2 is an alkyl radical
having 1 to 4 carbon atoms and is preferably methyl, to a
double-bond isomerization using basic catalysts at temperatures in
the range from 100 to 160.degree. C., and (b) transesterifying the
resultant conjuene fatty acid low-alkyl esters with glycerol to
give the corresponding glycerides and continuously distilling off
the lower alcohol released.
Surprisingly, it has been found that the desired conjugated
linoleic acid glycerides having a content, based on the content of
conjugated linoleic acid, of trans/trans double-bond isomers of
less than 3% by weight, and a content, based on the content of
conjugated linoleic acid, of c9, t11- and t10, c12-double-bond
isomers of, together, at least 95% by weight can be prepared in a
simple one-pot reaction, where, in the first step, an
alkali-metal-catalyzed double-bond isomerization is carried out and
then, without addition of further catalyst and under constant
reaction conditions, transesterification with addition of glycerol
is carried out.
DETAILED DESCRIPTION OF THE INVENTION
Starting Materials
Starting materials preferably used for preparing the conjugated
linoleic acid glycerides are fatty acid low-alkyl esters which have
a content of diunsaturated and/or triunsaturated acyl radicals of
more than 50, and in particular more than 60, mol %, for example
sunflower fatty acid, safflower fatty acid or rapeseed fatty acid
alkyl esters. Usually, methyl or ethyl esters are used as starting
material.
Double-Bond Isomerization
For isomerization of the isolated double bonds in the starting
esters, that is to say for forming the conjuene fatty acid esters,
generally basic catalysts of the type of alkaline metal hydroxides
or alkali metal alkoxides are used, in particular anhydrous or in
alcoholic solution. The amount used can be from 1 to 5% by weight,
based on the ester used. Typical reaction times are in the range
from 1 to 6 h, preferably from 2 to 4 h, and temperatures from 100
to 160.degree. C., preferably from 120 to 140.degree. C.
Transesterification and Work-Up
One of the essential advantages of the method is that it is a
one-pot reaction, that is to say the conjuene fatty acid esters
formed as intermediates need not be isolated, but can be directly
transesterified to glyceride with addition of glycerol. Generally,
it is not even necessary to add further catalyst. Usually, fatty
acid low-alkyl esters and glycerol are used in a molar ratio of
1:0.3 to 1:0.5, the amount usually being chosen such that it is
sufficient to form a random mono-/di-/triester mixture. The
transesterification can be carried out at temperatures in the range
from 100 to 160.degree. C., preferably from 120 to 140.degree. C.,
if appropriate under a reduced pressure from 50 to 100 mbar. The
alcohol released in the method is continuously removed from the
reaction equilibrium in order to contribute to product formation.
The catalyst is then neutralized by adding a mineral acid, for
example phosphoric acid, or an organic acid, for example lactic
acid and filtered with addition of filter aids, in order to obtain
a clear product. If desired, the glyceride can then be deodorized
in a thin-film evaporator.
EXAMPLES
Example 1
200 g of sunflower fatty acid methyl ester were charged together
with 6.4 g of potassium methoxide into a 500 ml 3-neck flask
equipped with stirrer, dropping funnel and reflux condenser and
heated in the course of 2 h to 130.degree. C. and held at this
temperature for 1.5 h. 48.1 g of glycerol were then added dropwise,
the mixture was further stirred at 130.degree. C. for 1 h and the
pressure was then reduced to 80 mbar. After a further stirring time
of 2 h at 130.degree. C., the batch was cooled to 75.degree. C.,
aerated with nitrogen and neutralized by adding phosphoric acid, in
which case brightening of the color was observed. A filter aid was
then added to the product which was filtered through a Beco C1
filter plate and deodorized using a thin-film evaporator. The
reaction product composition is shown in Table 1.
TABLE-US-00001 TABLE 1 Reaction product composition Composition %
by weight Total content of conjugated linoleic acid 61.0 c9, t11
isomer 30.0 t10, c12 isomer 29.4 c, c isomers 0.9 t, t isomers
0.9
Example 2
200 g of safflower fatty acid methyl ester were placed together
with 4.4 g of potassium tert-butyl oxide in a 500 ml 3-neck flask
equipped with stirrer, dropping funnel and reflux condenser and
heated in the course of 2 h to 130.degree. C. and kept at this
temperature for 1.5 h. 48.1 g of glycerol was then added dropwise,
the mixture was further stirred at 130.degree. C. for 1 h and the
pressure was then reduced to 80 mbar. After a further stirring time
of 2 h at 130.degree. C., the batch was cooled to 75.degree. C.,
aerated with nitrogen and neutralized by adding phosphoric acid, in
which case a brightening of the color was observed. A filter aid
was then added to the product, the mixture was filtered through a
Beco C1 filter plate and deodorized using a thin-film evaporator.
The reaction product composition is shown in Table 2.
TABLE-US-00002 TABLE 2 Reaction product composition Composition %
by weight Total content of conjugated linoleic acid 74.0 c9, t11
isomer 36.0 t10, c12 isomer 35.0 c, c isomers 1.4 t, t isomers
1.2
Comparative Example V1
320 g of fatty acid (conjugated linoleic acid: 76%, of which c9,
t11: 35.5% and t10,c12: 36.2%) and 35 g of glycerol were placed
together with 0.25 g of tin (II) oxalate, 4.4 g of potassium
methoxide in a 500 ml 3-neck flask equipped with stirrer, dropping
funnel and reflux condenser and heated in the course of 2 h to
210.degree. C. and kept at this temperature under a pressure of 800
mbar for 2 h. The pressure was then reduced to <30 mbar. The
batch was cooled to 75.degree. C., aerated with nitrogen and
neutralized by adding phosphoric acid. A filter aid was then added
to the product, the mixture was filtered through a Beco C1 filter
plate and deodorized using a thin-film evaporator. The reaction
product composition is shown in Table 3.
TABLE-US-00003 TABLE 3 Reaction product composition Composition %
by weight Total content of conjugated linoleic acid 76.0 c9, t11
isomer 30.3 t10, c12 isomer 28.5 c, c isomers 5.7 t, t isomers
11.1
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